In a LTE (Long Term Evolution) system, physical uplink channels mainly include a PUCCH (Physical Uplink Control Channel) and a PUSCH (Physical Uplink Shared Channel) and so on. The PUCCH is used for transmitting uplink control information, which includes uplink feedback such as ACK (Acknowledge)/NACK (Non-Acknowledge), CQI (Channel Quality Indication), RI (Rank Indication), and PMI (Precoding Matrix Indicator) and so on. PUSCH may only transmit Uplink Shared Channel (UL-SCH) data or may only transmit uplink control information, or may transmit both uplink shared channel data and uplink control information.
All User Equipments (UE) in a cell need to set transmission power of a physical uplink shared channel in every subframe. In an adjustment process of uplink closed loop power control, for a certain subframe i, the setting formula (or called as a power control formula, hereinafter referred to as formula 1) for the transmission power of its physical uplink shared channel (take dBm as a unit) is:PPUSCH(i)=min{PMAX,10·log10(MPUSCH())+O—PUSCH(j)+α·PL+ΔTF(i)+f(i)},
where PMAX represents an upper limit of transmission power;
MPUSCH(i) represents bandwidth used for transmitting the PUSCH in subframe i, that is the number of resource blocks used for transmitting the PUSCH in subframe i;
PO—PUSCH(j) represents target reference power. For the specific definition of variable j, please refer to relative standard documents of LTE, such as the definition in section 5.1.1.1 of TS 36.213 (LTE physical layer);
α represents a path loss correction factor;
PL represents path loss;
ΔTF(i) represents a transmission format offset parameter, wherein
When KS=1.25, ΔTF(i)=10·log10(2MPR·KS−1); when KS=0, ΔTF(i)=0;
KS is a parameter configured by RRC (Radio Resource Control) at a high layer; MPR=TBS/NRE, where TBS represents the size of a transmission block; NRE represents the number of resource elements, NRE=MPUSCH·NscRB·NsymbPUSCH, MPUSCH represents the bandwidth used for transmitting the physical uplink shared channel, NsymbPUSCH represents the number of SC-FDMA (Single Carrier-Frequency Division Multiple Access) symbols used for transmitting the PUSCH; NscRB represents the number of subcarriers (resource elements) contained in a resource block, which is used for representing the size of a resource block in a frequency domain. TBS and MPUSCH can be obtained according to a signaling in an initial PDCCH of a transmission block;
f(i) represents the power control correction function of subframe i.
As TBS represents the size of a transmission block, when there is only uplink control information but no uplink shared channel data sent over a physical uplink shared channel, the size of a transmission block is 0, that is TBS=0, then,ΔTF(i)=10·log10(2MPR·KS−1)=10×log10(20×1.25−1)==10×log100,
where ΔTF(i) is an infinite value, which is meaningless; this can lead to troubles in system realization. When there is only uplink control information but no uplink shared channel data sent over a physical uplink shared channel, the power control of the physical uplink shared channel can not be realized, the transmission performance of uplink control information can be affected, and thereby the overall performance of a system can be caused to decline.